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Compact total irradiance monitor: Flight demonstration



Dave Harber, John H. Lehman, Nathan A. Tomlin, Christopher Yung, Malcolm White, Zach Castleman, Ginger Drake, Samuel Van Dreser, Nat Farber, Karl Heurman, Joel Rutkowski, Alan Sims, Jacob Sprunck, Cameron Straatsma, Isaac Wanamaker, Wengang Zheng, Greg Kopp, P. Pilewskie, Michelle Stephens


The long-term balance between Earth's absorption of solar energy and emission of radiation to space is a fundamental climate measurement. Total solar irradiance (TSI) has been measured from space, uninterrupted, for the past 40 years via a series of instruments. The Compact Total Irradiance Monitor (CTIM) is a CubeSat instrument that will demonstrate next-generation technology for monitoring total solar irradiance. It includes novel silicon-substrate room temperature vertically aligned carbon nanotube (VACNT) bolometers. The CTIM, an eight-channel 6U CubeSat instrument, is being built for a target launch date in late 2020. The basic design is similar to the SORCE, TCTE and TSIS Total Irradiance Monitors (TIM). Like TSIS TIM, it will measure the total irradiance of the Sun with an uncertainty of <0.01% and a stability of <0.001%/year. The underlying technology, including the silicon substrate VACNT bolometers, has been demonstrated at the prototype-level. During 2019 we will build and test an engineering model of the detector subsystem. Following the testing of the engineering detector subsystem, we will build a flight detector unit and integrate it with a 6U CubeSat bus during late 2019 and 2020, in preparation for an on-orbit demonstration.
SPIE Conference Proceedings


Solar irradiance, cubesat, carbon nanotubes, total solar irradiance (TSI)


Harber, D. , Lehman, J. , Tomlin, N. , Yung, C. , White, M. , Castleman, Z. , Drake, G. , Van Dreser, S. , Farber, N. , Heurman, K. , Rutkowski, J. , Sims, A. , Sprunck, J. , Straatsma, C. , Wanamaker, I. , Zheng, W. , Kopp, G. , Pilewskie, P. and Stephens, M. (2019), Compact total irradiance monitor: Flight demonstration, SPIE Conference Proceedings, [online],, (Accessed June 13, 2024)


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Created August 29, 2019, Updated October 12, 2021